a The MDPV category was created for the Interim Tier 2 and Tier
2 vehicle emissions standards. This category was specifically designed to help
bring passenger vehicles (such as large sport utility vehicles and passenger
vans) over 8,500 pounds GVWR into the Tier 2 program. MDPVs are defined as any
complete heavy-duty vehicle less than 10,000 pounds GVWR designed primarily
for transportation of persons, including conversion vans (i.e., vans which are
intended to be converted to vans used primarily for transporting people). This
does not include vehicles that have 1) a capacity of more than 12 persons total,
or 2) are designed to accommodate more than 9 persons seated rearward of the
driver's seat, or 3) have a cargo box (i.e., a pickup-bed or box) of six feet
or more in interior length. Prior to Tier 2 standards, these vehicles would
have been regulated as light heavy-duty trucks.

b Diesel MDPVs can continue to use light heavy-duty truck standards
for new vehicle certification until 2008. Note that these standards are measured
in grams per brake horsepower-hour (g/bhp-hr). Beginning in 2008, MDPVs must
use the same on-chassis testing procedure as heavy light-duty trucks (catgories
LDT3 and LDT4) and must meet standards for MDPVs. Beginning in 2009, MDPVs must
meet the same standards as light heavy-duty trucks, except MDPVs are not required
to meet Supplemental Federal Test Procedure standards.

cThe cold CO emissions standard is measured at 20 0F
(rather than 75 0F) and is applicable for a full useful life of 5-years/50,000-miles.

d Smoke opacity is expressed as a percentage for acceleration, lugging,
and peak operation modes. Lugging occurs when a vehicle is carrying a load.

eManufacturers can opt to certify vehicles for a useful life of
15 years/150,000 miles and have either 1) intermediate useful life standards
waived or 2) receive additional NOx credits.

fThe term "tier" refers to a level of standards for specific
years. Interim 2 refers to an intermediate level of stndards that moves manufacturers
toward compliance with Tier 2 standards. Tier 2 and interim Tier 2 standards
are established as "bins." Each bin is a set of standards for NOx,
CO, NMOG, formaldehyde, and particulates (HC and NMHC standards are dropped
for Tier 2 and Interim Tier 2). Manufacturers may certify any given vehicle
family to any of the bins available for that vehicle class as long as the resulting
sales-weighted corporate average NOx standard is met for full useful
life. The Tier 2 corporate average NOx standard is 0.07 grams/mile.
Interim corporate-based average NOx standards are based on vehicle type. The
interim corporate sales-weighted average for MDPVs is 0.6 grams/mile. Tier 2
MDPV standards will be phased in during 2008 and 2009. In 2008, 50% of MDPVs
must meet Tier 2 standards; the other 50% of MDPVs must meet interim Tier 2
standards. Beginning in 2009, all MDPVs must meet Tier 2 standards.

gDiesel MDPVs are not required to meet intermediate life standards
during this time period.